No matter how safe you try to be, if you surf the internet you will eventually get infected with spyware and adware.

Spyware is a program that infects your computer and can track all your actions, including watching which websites you visit, your keystrokes, basically anything you do on your computer the spyware can watch and track. It then sends the data back to a company or person that usually use this information to target certain marketing efforts to you (usually in the form of spam emails).

Adware is a program that attaches itself to your computer and jams advertisements in your face. Some of the ways it can display itself are as follows; consent pop-up windows (that have nothing to do with a site you happen to be browsing through), strange hotlink keywords in a block of text (like if your readng about a women's cancer survival and there are words in the story that are links to "breast enhancement" sites or worse, it is probably adware sticking those links in through your browser and that website really doesn't have any links in that story.)

Both of these are an invasion of your privacy and can cause your computer to run slow and possibly crash.

Ad-Aware SE is one of the most popular spyware/adware detection and removal programs availible for free.

WARNING!!! This program scans your registry and you have to decide which files to delete. DO NOT DELETE any files unless you know what you are doing. You can cause permanent damage to your PC by deleting the wrong files. I suggest you visit http://computercops.biz and request advice before deleting anything.

This is a great program and can rid your system of the bad programs that other adware/spyware/virus/worm removers can't quite get rid of. But use caution, it allows you easy access to delete files that may not be wise to delete. Use this program only with experienced people to assist you.

HijackThis lists the contents of key areas of the registry and hard drive--areas that are used by both legitimate programmers and hijackers. The program is continually updated to detect and remove new hijacks. It does not target specific programs and URLs, just the methods used by hijackers to force you onto their sites. As a result, false positives are imminent, and unless you're sure about what you're doing, you should always consult with knowledgeable folks before deleting anything.

Spybot - Search & Destroy can detect and remove a multitude of adware files and modules from your computer. Spybot also can clean program and Web-usage tracks from your system, which is especially useful if you share your computer with other users. Modules chosen for removal can be sent directly to the included file shredder, ensuring complete elimination from your system. For advanced users, it allows you to fix registry inconsistencies related to adware and to malicious program installations. The handy online-update feature ensures that Spybot always has the most current and complete listings of adware, dialers, and other uninvited system residents.

Version 1.3 adds enhanced immunization features, an improved interface, and integration of BrowserManager for spyware detection, plus the new Hosts File feature and bug fixes.